Sodium cyanoborohydride → 5-Bromo-2-methyl-8-nitro-1,2,3,4-tetrahydroisoquinoline

Participants

Reaction Steps

Into a 500 mL 3-necked round bottom flask was placed a solution of Ni(NO3)2.6H2O (12.6 g, 43.33 mmol) in CH3OH (200 mL). To the mixture was added 5-bromo-8-nitro-N-methylisoquinolinium iodide (33.33 g, 84.38 mmol). To the above was added NaCNBH3 (10.6 g, 168.68 mmol) in several batches. The resulting solution was allowed to react, with stirring, for 5 hours while the temperature was maintained at room temperature. The reaction progress was monitored by TLC (ethyl acetate/petroleum ether=1:5). The resulting solution was concentrated by evaporation under vacuum using a rotary evaporator. The residue was dissolved with 800 mL of H2O. Adjustment of the pH to 8-10 was accomplished by the addition of NaOH (5%). A filtration was performed. The resulting solution was extracted 2 times with 800 mL of ethyl acetate and the organic layers combined and dried over Na2SO4. The residue was purified by eluting through a column with a 1:5 ethyl acetate/petroleum ether solvent system. This resulted in 19.3 g (83%) of 5-bromo-2-methyl-8-nitro-1,2,3,4-tetrahydroisoquinoline as a yellow solid.

Provenance & Evidence